Apparatus for correlating two variables whose relationship is affected by a third



United States Patent Charles B. l'laentze Scottsdale, Arizona 823,089

May 8, 1969 Dec. 8, 1970 Burroughs Corporation Detroit, Michigan a corporation of Michigan Inventor Appl. No. Filed Patented Assignee APPARATUS FOR CORRELATING TWO VARIABLES WHOSE RELATIONSHIP IS AFFECTED BY A THIRD 14 Claims, 7 Drawing Figs.

US. Cl. 235/86, 235/71 Int. Cl G060 27/00, G06c 3/00 Field ofSearch 235/86,71,

[56] References Cited UNITED STATES PATENTS 2,296,312 9/1942 Sheehy et a1 35/3 2,527,776 10/1950 Taaffe 235/71 3,330,478 7/1967 Berry 235/61 3,391,864 7/1968 Adler 235/71 Primary ExaminerStephen J. Tomsky Attorney-Carl Fissell, Jr.

ABSTRACT: A conversion table apparatus which utilizes two members representative, respectively, of an independent variable and a dependent variable and determines the relationship of these variables as it is affected by a second independent variable represented by the environment to which the two members are exposed.

PATENTEU HEB 8 I970 saw 1 {IF 2 INVliN'l'UR. CHARLES B. HAENTZE ATTORNEY APPARATUS FOR CORRELATING TWO VARIABLES WHOSE RELATIONS IS AFFECTED BY A T f I BACKGROUND OF THE INVENTION This invention relates generally to conversion tables and more particularly to conversion table apparatus for correlating two variables whose relationship is affected by a third variable.

It is customary to have conversion tables printed or otherwise reproduced in two columns upon essentially homogeneous material such as paper, photoreproduction material, plastics, metals, etc. The two columns of equivalent numbers are placed side by side, as in reference sheets, books and slide rules, or on separate parts of slide rules. In any case, the relationship between the values of the independent variable in one column and the corresponding values of the dependent variable in the other column is fixed.

Where a second independent variable, such as temperature, for example, produces a change in the relationship between values, a correction factor must be applied, because the relationship will otherwise be correct only for one value of the second independent variable.

The correction factor is generally applied by one of several methods. One method is to use'an additional table or graph which gives the value of the correction factor for each value of the second independent variable, and then to multiply arithmetically, or by means of the slide rule. Another method is to record the table in the form of a three-column table and to use a straight line to connect the values of the two independent variables with the third column, from which the required value is read. A third method is to place both tables on a slide rule in such fashion that the corrected value can be obtained by typical manipulation of the parts of the slide rule.

These methods of applying the correction factors are accompanied by several disadvantages. For example, manipulation and computation may be required, so that in such cases, there would exist the possibility of introducing human error. In the case of the three-column table, table length is severely limited, so that accuracy and resolution are limited; and accuracy is further dependent upon the straightness of the straightedge. Also, three-column tables are soon smeared beyond usefulness if pencil or ink is used directly, thereby necessitating auxiliary devices such as transluscent overlay sheets or a transparent straightedge. Where the tables are placed on a slide rule, continued use will introduce wear, so as to cause errors by misalinement or weathering. Furthermore, in the case of the three-column table, and in the case of the slide rule and also possibly in the case of the first-mentioned method, adequate lighting is required to make the fine divisions or graduations of the tables readily visible. Where there are intermediate values in the tables, such as in the first method, and possibly also in the second and third methods, these intermediate values require decisions on the part of the operator, so that time delays or further human error may also be introduced. Finally, none of the three methods discussed is readily adaptable to direct machine readout.

SUMMARY OF THE INVENTION An object of the invention is to provide a conversion table apparatus which overcomes the disadvantages outlined above.

Another object of the invention is to provide a set of tabular equivalents which are automatically compensated for an ambient condition.

Another more specific object of the invention is to provide a conversion table apparatus which automatically applies the correction factor.

A further object of the invention is to provide a conversion table apparatus which is adaptable to visual and/or direct machine readout.

Still another object of the invention is to provide a conversion table apparatus which is simple to use and inexpensive to manufacture.

In accordance with the above objects and considered first in one of its broader aspects, apparatus according to the invention for correlating two variables whose relationship is affected by a third variable may comprise two elongate members having different expansion rates when subjected to an environment representative of the third variable. Each member carries a column of values representative of one of the two variables, and the members are so arranged that corresponding values of the members can be sensed. Means is provided for interconnecting one end of the members so that their unconnected portions are free to assume whatever length the third variable environment causes them to have.

The invention will be more clearly understood when the following detailed description of th e preferred embodiment thereof is read in conjunction with the accompanying drawing which is described below.

BRIEF DESCRIPTION OF THE DRAWING FIG. I is a isometric view of a conversion table apparatus constructed in accordance with the invention.

FIG. 2 is an enlarged isometric view of the apparatus of FIG. I, but with certain parts omitted.

FIG. 3 is an enlarged view of a fragment of the apparatus of FIG. 2 and with parts broken away to more clearly reveal other parts.

FIGS. 4-7 show several conditions of alinement which might be encountered in reading a decimal numbers tape and a binary numbers tape.

DESCRIPTION OF THE PREFERRED EMBODIMENT The invention has application to conversion tables for different kinds of variables and physical effects, however, for purposes of illustration it will be assumed that a primary independent variable is decimal numbers, that a dependent variable is binary numbers produced by or used by some device which is sensitive to ambient temperature and that a secondary independent variable is ambient temperature. Therefore, the description will be directed to apparatus for providing the binary equivalents of decimal numbers, corrected for temperature.

The conversion table apparatus may include a housing 10 (FIG. 1) provided with two windows 12 and 14. The window 12 is constructed so as to permit viewing the decimal numbers of a decimal numbers tape 16 (FIG. 2) while the window 14 is constructed so as to permit viewing of binary numbers in the form of punched holes 17 in the binary numbers tape 18.

Rotatably journaled in the housing 10 are shafts 20 and 22. Two drums 24 and 26 are secured on the shaft 20. Two drums 28 and 30 are mounted on the shaft 22. One of the drums 28 and 30 is secured on the shaft 22 while the other one of the drums 28 and 30 is freely mounted on'the shaft 22 but is coupled to the other drum thereon or to the shaft 22 by any suitable means so as to keep its associated tape in a taut condition, as will appear more clearly shortly hereinafter. In the illustrated embodiment of the invention, the drum 28 associated with the dependent variable tape or binary numbers tape 18 has been chosen, for purposes of illustration, to be secured on the shaft 22 while the drum 30 has been chosen to be yieldably coupled to the drum 28, and thereby to the shaft 22 by means of a torsion spring 32 which urges the drum 30 to follow the drum 28 in a clockwise direction, as viewed in FIG. 2.

To keep the tapes 16 and 18 in a taut condition, the shaft 22 may be urged in the clockwise direction, as viewed in FIG. 2, by any suitable device such as a counterweight 34 suspended from a cable 36 which is connected to a spool 38 secured to the shaft 22.

In some cases, it may be desirable to provide some means for keeping the internal apparatus, shown in FIG. 2, from moving or creeping due to conditions of vibration, and for balancing the force exerted by counterweight 34. For such purpose, a braking mechanism 39 may be used for applying a suitable drag on the shaft 20. The mechanism 39 may include a brake lever 40 pivotally mounted on a pin 42 (FIG. 1) secured to the housing and yieldably urged against the shaft by means of a tension spring 64, suitably anchored to the housing 10.

The tapes 16 and 18 are fabricated of dissimilar materials and each carries a list or column of numbers or values which may be printed, etched, engraved or otherwise recorded thereon. The decimal numbers tape 16 carries a list of decimal numbers and the binary numbers tape 18 carries a corresponding list of binary numbers formed by means of the holes 17 punched in the tape. The spacing or pitch of the numbers on each tape is identical when the temperature of the two tapes is that at which the individual numbers correspond without temperature compensation which might be, for example, 20 C.

Tape 16 is rolled up on drums 24 and 30 while tape 18 is rolled up on drums 26 and 23. The drums that support each tape are fabricated of the same material as the tape they support, so that drums 24 and 30 are fabricated of the same material as tape 16, and drums 26 and 28 are fabricated of the same material as tape 18. Thus, as the temperature changes, the diameter of each drum changes in precisely the same proportion as the length of each turn of tape wrapped upon it, thereby eliminating the possibility of any slipping, binding or stretching of the tape.

The tapes 16 and 18 are connected physically to one another only at the point where their values are equivalent regardless of the temperature, which might be, for example, at the point where decimalnumber 0 equals binary number 0 This point is represented in FIG. 3 by the broken line 16 at which decimal number 0 will always be in line with binary number 0. It is understood that binary number 0 is on the line 46 and is represented on the tape 18 by the absence of binarycoded punched holes 17. The tapes 16 and 18 are effectively interconnected at line 46 by having one end portion 47 and 19 of the tapes suitably connected to the respective drums 241 and 26, as by means of cement 51. At all other points, the tapes 16 and 18 are independent of each other and free to assume whatever overall length the ambient temperature may cause them to have.

As the temperature deviates from that at which the two sets of values on the tapes 16 and 18 correspond, such as 20 C for example, the free ends of the tapes extending rightwardly from the shaft 20 (FIG. 2) and rolled up on the drums 28 and 30 will move out of alinement since the tapes are constructed of dissimilar materials. If the binary numbers tape 18 were constructed of stainless steel, for example, and the decimal num bers tape 16 were constructed on lnvar, for example, the stainless steel tape would elongate more than the lnvar tape with rising temperature. Thus, the temperature correction factor will be applied automatically by displacing the values of the tapes 16 and 18 an amount directly proportional to their value and directly proportional to the change in temperature. Since a finite space is required for each entry, only a fraction of all entries will line up opposite each other as the tapes 16 and 18 change length. This condition will appear more clearly later on when FIGS. 47 are discussed. With few exceptions, a given entry on one tape will be closer to one entry on the other tape than to any other entry on the other tape. Where the entries differ by only the least count or sensitivity of the device which is to use their values, a detent device may be employed to stop the dependent variable tape 18 at the value nearest to the value selected on the tape 16.

FIGS. 4-7 illustrate four conditions of alinement which might be encountered at different places on the tapes due to changes in temperature. The tapes 16 and 18 are brought to any desired reading position by rotating the appropriate one of crank handles 48 and 50 (FIG. 2) secured to the shafts 20 and 22, and the tapes are then detented therein by means of a detent sprocket wheel 52 fixed on a shaft 54 which is suitably journaled for rotation in the housing 10. The detent sprocket wheel 52 is provided with a circular row of sprocket pins 56 which engage sprocket holes 58 in the binary tape 16. The

wheel 52 is also provided with arcuate notches 57 for receiving the arcuate end 55 of a detent spring 59 secured to the housing 16. By detenting the tape 111, the punched holes 17 of the binary number corresponding to the decimal number to be read will be exactly centered on the centerline 60 of the windows 12 and 1 in case it is desired to use a static reader which may be connected to some device such as a digital computer, for example, for visual reading only, the detent may be omitted.

Accordingly, in order to obtain the binary equivalent of a decimal number automatically corrected for temperature the corresponding values can be read in the windows 12 and 14, either visually and/or by means of a static reader device.

In FIG. 41, the decimal number 710 is exactly centered in the window 12 on the centerline 60 so that the decimal value corresponding to the binary number in window 14 would be read as 716.

FIG. 5 illustrates a typicfl type of alinement in which the number 526 is not exactly centered in the window 12 but is nearer to the centerline 60 of that window than other entries on the tape 16. Therefore, the decimal value on the tape 16 in FIG. 5 would be read as 526.

FIG. 6 also illustrates a typical type of alinement in which the decimal number 663 is farther removed from the centerline 60 of the window 12 than the number 526 of FIG. 5, however, the number 463 is still closer to this centerline than other entries on the tape 16 so that the decimal reading for this tape for FIG. 6 would by 463.

FIG. '7 illustrates a worst-case type of alinement in which two decimal numbers 2131 and 289 are equally distant from the centerline 611 of the window 12. For this special case, there will be a half-bit error in reading, however, this should be within the design tolerance of any system utilizing the invention. 1n order to provide the type of viewing illustrated in FlGS. -47, it is noted that the window 12 must be high enough, as shown in HG. '7, to show two decimal numbers simultaneously.

A requirement of prime importance is that the difference between the coefficients of environmental expansion of the two tape materials used be as close as possible to the correction factor required for the particular environment and constant over the range of values representing environmental changes for which correction is required. In the statement of this requirement, the word environmental" is used generically so as to apply to all environments, including ambient heat or temperature environments, in which the invention can automatically apply a correction factor for effects other than as well as including temperature. Therefore, a restatement of this requirement, as it applies to the specific apparatus illustrated in a heat or temperature environment, is that it is of prime importance that the difference between the coefficients of thermal expansion of the two tape materials used be as close as possible to the thermal correction factor required and constant over the temperature range for which correction is required.

As an example, let it be assumed that the correction required for temperature compensation is 0.00l percent per centigrade degree. This is equivalent to 10-- per degree, and any combination of metals may be selected for which the difference in their thermal expansion coefficients is 10- per degree. Usable combinations include lnvar-stainless steel (0.9 X 10- /C vs. 10.0 X l0 /C) or low bronze-stainless steel (21 X l0 /C vs. 11 X l0 /C).

While the thermal expansion coefficients of the practical metals and alloys is currently limited to about 33 X l0 /C, stable plastics are available with coefficients exceeding 250 X l0 Thus, in combination with lnvar or some other lowcoefficient metal, correction factors as high as 0.025 percent per centigrade degree can be provided.

if it should be required to provide a correction factor greater than 0.025 percent per centigrade degree, or if the use of plastics should be considered to be undesirable, then it would be necessary to amplify the efiect of thermal expansion by some method applicable to a tape configuration.

Correction factors for effects other than temperature can be provided by means of the present invention by choosing tapes which will change length differently when subjected to the required effect. For example, one tape can be made of nickel or some other magnetostrictive material, while the other tape can be made of a nonmagnetostrictive material having the same temperature coefficient. In this case, the elongation of the nickel tape will be a function of the magnetic field present. Another example would be the use of two tapes of like thermal expansion coefficient material but different susceptibility to water vapor in the air, thus providing a humidity compensation factor.

It is also possible to provide compensation for more than one secondary independent variable by selecting materials having the desired combination of susceptibilities.

It is also possible, by using a truly elastic material for one tape, to set in a correction factor for some effect for which no adequately susceptible material is available. In this case, the takeup reel for the elastic tape would be rotated and then locked with respect to the other takeup reel an amount proportional to the maximum correction required (the correction at the free ends of the tapes). Thus the entries would be shifted an amount proportional to their value and proportional to the correction factor desired.

While there has been disclosed a specific apparatus to exemplify the principles of the invention, it is to be understood that this is the preferred embodiment of the invention and that the invention is capable of being constructed in a variety of shapes, sizes and modifications without departing from its true spirit and scope. Accordingly, the invention is not to be limited by the specific conversion table apparatus disclosed, but only by the subjoined claims.

Iclaim:

1. Apparatus for correlating two variables whose relationship is affected by a third variable comprising two elongate members having different expansion rates when subjected to an environment representative of said third variable, each member carrying a column of values representative of one of said two variables and arranged so that corresponding values of said members can be sensed, and means for interconnecting one end of said members so that their unconnected portions are free to assume whatever length said environment causes them to have.

2. Apparatus for correlating a first independent variable and a dependent variable and automatically applying a correction factors to values of the dependent variable for a series of values of a second independent variable where the relationship between the first independent variable and the dependent variable is affected by the second independent variable comprising two elongate members having different environmental expansion rates when subjected to an environment representative of said second independent variable, the difference between the coefficients of environmental expansion of said members being as nearly equal to said correction factor as can be obtained, one member carrying a column of values representative of said first independent variable and the other members carrying a column of values representative of said dependent variable and said columns being arranged so that corresponding values of said members can be sensed, and

means for interconnecting one end of said members so that the remaining portions of said members are free to assume whatever length said environment causes them to have.

3. Apparatus according to claim 2 wherein said difference between the coefficients of environmental expansion is substantially constant over the range of said series of values of said second independent variable.

4. Apparatus for correlating two variables whose relationship is afiected by a third variable comprising first and second drums, two elongate tapes having different expansion rates when subjected to an environment representative of said third variable, each tape carrying a column of values representative of one of said two variables and arranged so that corresponding values of said members can be read, means for connecting one endof each tape to one of said drums so that the remainmg portions of the tapes are free to assume whatever length said environment causes them to have, and means for rotating said drums as a unit so as to wind or unwind the tapes thereon for positioning selected values on the tapes to a reading station.

5. Apparatus according to claim 4 wherein said tapes are constructed of dissimilar materials.

6. Apparatus according to claim 5 wherein each drum is constructed of the same material as the tape to which it is connected.

7. Apparatus according to claim 6 characterized further by the provision of means for holding said first and second drums stationary when said rotating means is not active, and takeup means for maintaining the tapes in a taut condition.

8. Apparatus according to claim 7 wherein said takeup means comprises third and fourth drums on each of which is wrapped the free end of one of said tapes, and means for urging said third and fourth drums to rotate in the takeup direction.

9. Apparatus according to claim 8 wherein each of said third and fourth drums is constructed of the same material as the tape which is wrapped upon it.

10. Apparatus according to claim 9 wherein said urging means comprises a rotatable shaft, said third drum is secured on said shaft, said fourth drum is free on said shaft, means is provided for yieldably coupling the fourth drum to the third drum, and means is provided for urging said shaft to rotate.

lll. Apparatus according to claim 10 characterized further by the provision of means forming a said reading station to permit reading of corresponding values on said tapes, said reading station being constructed to permit simultaneous location for reading of one value on one of the tapes and one or two corresponding values on the second tape.

12. Apparatus according to claim 11 wherein the values on said second tape represent an independent variable and the values on said one of the tapes represent a dependent variable.

13. Apparatus according to claim 11 characterized further by means for detenting one of said tapes when selected values on the tapes are positioned to said reading station by rotation of said rotating means.

14. Apparatus according to claim 13 wherein the values on the tape which is detented represent a dependent variable and the values on the other taperepresent an independent variable. 

